In the title compound, C(20)H(28)O(4), a diterpenoid isolated from the roots of Premna obtusifolia (Verbenaceae), the five-membered ring is in a half-chair conformation. One six-membered ring exists in a twisted-boat conformation while the other is in half-boat conformation. The crystal packing is stabilized by inter-molecular O-H⋯O and weak C-H⋯O inter-actions, generating (001) sheets.

ABSTRACT A continuing search for tumor inhibitors from plant sources has yielded over two hundred extracts with reproducible growth-inhibitory activity. Systematic fractionation, guided by assay in cell culture and animal tumor systems, has led to the isolation of the active principles of more than sixty plants. Chemical studies of novel sesquiterpene lactones, diterpenoid quinone methides, ste...

In the title compound, C(30)H(41)NO(6), the three six-membered rings adopt chair conformations and the stereochemistry of the A/B and B/C ring junctions are trans. The five-membered ring D adopts an envelope conformation, with the methyl-ene C atom as the flap. The title compound was synthesized via esterification, Tollens reaction, 1,5-hydride shift from the natural tetracyclic diterpenoid iso...

Three new rearranged ent-kaurane-type diterpenoids (1-3) and seven new ent-kaurane-type diterpenoids (4-10) have been isolated from the liverwort Jungermannia atrobrunnea. Their structures were determined by extensive spectroscopic techniques and X-ray crystallographic analysis. The absolute configurations of these compounds were clarified by CD spectroscopic studies. Compound 1 is the first ex...

The title compound, C(27)H(34)O(5), a beyerane-type diterpenoid prepared by peroxidation and benzoyl-ation of isosteviol, contains a fused six-membered ring system. The O atoms of the benzoic ester and the lactone are disordered with occupancy ratios of 0.6 (4):0.4 (4) and 0.6 (2):0.4 (2), respectively. Three cyclo-hexane rings have chair conformations, whereas the remaining lactone ring adopts...

The present review is focussed on the structural elucidation of bicyclic and tricyclic diterpenoid title compounds isolated from Pseudopterogorgia species, displaying a direct relationship with biosynthetic precursor GGPP (regular isoprenoid skeletons). A compilation 1 H 13 C NMR spectroscopic data presented grouped by similar spin systems. Apparent inconsistencies or potential missassignments ...

Four new neo-clerodane diterpenoid alkaloids, named scutebarbatines I-L (1-4), were isolated from the whole plant of Scutellaria barbata D. DON. Their structures were established on the basis of detailed spectral analyses. In vitro, the four new compounds showed significant cytotoxic activities against three human cancer lines (HONE-1 nasopharyngeal, KB oral epidermoid carcinoma, and HT29 color...

This review describes strategies for the chemical synthesis of xenicane diterpenoids and structurally related metabolites. Selected members from the four different subclasses of the Xenia diterpenoid family, the xenicins, xeniolides, xeniaphyllanes and xeniaethers, are presented. The synthetic strategies are discussed with an emphasis on the individual key reactions for the construction of the ...

A new rare casbane-type diterpenoid 1 and two new cembrane diterpenoids 2, 3 were isolated from an Okinawan soft coral, Lobophytum sp., together with four known cembrane diterpenoids 4-7. Their structures were elucidated by extensive analysis of spectroscopic data (1D and 2D NMR, IR, and MS) and a molecular modeling study. The new isolates showed weak anti-bacterial activity, mild cytotoxicity ...

The new title diterpenoid compound, C(20)H(30)O, is a natural product isolated from Tetra-clinis articulata wood via chloro-form extraction. The asymmetric unit contains four mol-ecules with the same S,S configuration, deduced from the chemical synthesis. Indeed, an overlay analysis, calculated using structure-matching software, shows that the four mol-ecules can be superimposed. The central ri...